This invention relates to a magnetic head device for recording a signal onto a disk-shaped rotary recording medium and reproducing it therefrom, and more particularly, to a magnetic head device using jointly an optical servo and a photo detector cell for recording and reproducing.
A disk-shaped recording medium usually comprises a floppy or flexible disk (hereinafter simply referred to as a disk). A floppy disk drive (hereinafter simply referred to as a disk drive) is used for recording data to the disk and reproducing data from the disk. In recent years, it has become desirable to increase the memory capacity. By increasing the capacity of the disk, improvements in track density (TPI) and data density (BPI) became indispensable. Track density is dependent upon the precision of controlling an absolute position of the magnetic head with respect to the radial direction of disk.
Magnetic heads conventionally used have a Read/Write (hereinafter referred to as a R/W) core structure with a gap for R/W and a core structure for erasing fixed on a base body by means of adhesive agent. The core arrangement is mounted on a carriage through a gimbal support.
One method known for controlling the radial track position of such a magnetic head, comprises driving the carriage by means of a pulse motor, to perform a track seeking operation of the magnetic head through a stepping operation of the pulse motor. However, this method has limitations in use with disks having high density tracks. Therefore, a tracking servo system in which servo signals were recorded on a track was devised.
However, the available recording area for data signals is decreased due to the need to record servo signals. For this reason, it was realized that it is difficult to provide a disk drive which is applicable to the large capacity disk system.